In rare cases they can drop from munsies in the dungeon.
They will drop from bosses in the dungeons.

Ascalon catacombs is confirmed by many players that a run killing teh bosses will have 41 tokens as drops from killing all bossies.
It has 3 different possible paths you can take, which opens after doing the personal story mode dungeon run. The personal story mode run gives you a headpiece dungeon armor part beside some tokens.